Why do Christians pray?
I mean, God is omniscient, and pretty much knows what you are thinking before you even think of it. Every time I go over to a Christian person's house for dinner, which is fairly often, I often ask myself that question when we pause to pray. "We" being the 3rd person way of being polite, since it is really "They" who pause ( With a curious look on my face as I look at the somber lot talking to someone who isn't there). What could you possibly say, or ask for, that God in his omniscience, doesn't already know?
What do they hope to accomplish? Do they want to change God's mind? Do they want to prevent a catastrophy that God already KNOWS about? Maybe save a brother or sister with cancer that God already knows will live or die. I mean, it's not like he will change his mind since he already knows what will happen. So in a way, prayers are futile. God is inert, he can't be changed because he lives at all times, knows everything and therefore has already made up his mind, so to speak (curiously he can't even make up his own mind in the first place because he existed forever).
Maybe it's a way to tell ourselves that maybe we can change future events, even though we really can't since God has already been there-done-that and knows exactly what is going to happen. He even knows that you would ask him, and has already issued a response before you even asked! Wow!
Man has always wanted to be able to change, or at least see into the future. The earliest civilizations had there own methods. The Romans had birds wings, some had tea leaves others had special cards, ours even has a 1800 number for convenience. I believe it is part of the human condition to fear the future, to want to change it, to make it better somehow. That is both inspiring and curious to me.